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Bloc I - Reproduction > Sept7 M3-Pelvis_Anatomy_lecture_5 > Flashcards

Sept7 M3-Pelvis_Anatomy_lecture_5 Flashcards

1
Q

borders of the anal triangle

A
  • ischial tuberosities (imaginary line between them)
  • sacrotuberous ligaments
  • coccyx
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2
Q

ischiorectal (ischioanal) fossa is what

A

two triangles on either side of the anus mostly filled with fat + levator ani

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3
Q

(imp) borders of the ischiorectal fossa

A
  • base (superficial) = skin
  • lateral wall = lower part of obturator internus
  • medial wall = levator ani
  • fossa continuous with the deep perineal pouch (of the UG triangle). nothing separating them. for deep perineal pouch, superficial base was perineal membrane and deep base was also levator ani
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4
Q

structures visible in a coronal view of the ischiorectal fossa

A
  • anal canal (middle)
  • levator ani (medial wall of the fossa + going oblique and upwards laterally)
  • lot of fat below, lat to levator ani (fat pad)
  • obturator internus (lateral wall of the fossa)
  • pudendal canal (just medial to obturator internus, contains pudendal vessels and n)
  • Colle’s fascia (superficial fascia marking start of the superficial base). extends from ischium to anal canal
  • skin (base)
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5
Q

anal canal structures in coronal view

A
  • levator ani
  • anorectal junction (end of smooth features of rectal ampulla. is end of the rectum
  • anal columns and sinuses below the ARJ (like prostatic crests on either side of prostate and sinus in middle). are in the anus
  • anal valve = narrowing of anal canal at level of the bottom of the anal sinuses and columns
  • pectinate line = line between endoderm-derived hindgut (above) and ectoderm-derived anal pit (below)
  • anal pecten (region between pectinate line and anocutaneous line)
  • anocutaneous line (division between anus and skin)
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6
Q

clinical significance of the pectinate line in the anal canal

A
  • internal hemorrhoids are above it and are not painful

- external hemorrhoids are below it and are painful

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7
Q

muscles surrounding the rectum

A
  • inner circular layer

- outer longitudinal layer

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8
Q

2 anal sphincters and what they cover

A

internal anal sphincter (more medial): covers upper two thirds of anal canal)
external (more lat): covers lower two thirds of anal canal)
the two overlap in the middle third of the rectum

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9
Q

control of anal sphincters (which is voluntary?)

A
  • internal = involuntary. always contracted, SS tone

- external = voluntary (somatic inn in this region is from pudendal n, which gives inferior rectal nerves)

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10
Q

internal anal sphincter is what

A

muscle of inner circular muscular coat around rectum coming down around anal canal

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11
Q

external anal sphincter is what

A

levator ani coming down reaching kink of rectum (of puborectalis sling)

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12
Q

3 parts of the external anal sphincter

A

top to bottom

  • deep
  • superficial
  • subcutaneous
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13
Q

bloody supply to the anus

A

inferior rectal a and v coming from internal pudendal a and v (which come from internal iliac a and v)

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14
Q

inn to anus

A

inferior rectal nerves coming from pudendal n

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15
Q

pudendal canal (Alcock canal) def + is where

A
  • a passageway within the obturator fascia (fascia of obturator internus) on lat wall of ischiorectal fossa) for the internal pudendal a and v + pudendal n
  • is inferior to the obturator foramen
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16
Q

how to see internal pudendal a from the gluteal region

A

look for ischial spine (look underneath the area of the inferior gluteal a)

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17
Q

what internal pudendal a does after swings back in perineum around ischial spine

A

travels forward to reach the UG triangle (travels on side of ischiopubic ramus, below obturator foramen)

18
Q

diff arteries that come off the internal pudendal a as it goes in the pudendal canal

A
  • start (in the back): gives off inferior rectal a
  • end (front): gives off perineal branches that go in deep and sup perineal pouches
  • distally becomes the dorsal artery of the penis or clitoris
19
Q

why coccygeus m. is a key point in the pelvis

A
  • points to the ischial spine
  • is deep to the SS ligament
  • start of the tendinous arch
20
Q

internal pudendal a travels where with respect to coccygeus

A

below piriformis (medial to it), above coccygeus (lateral to it)

21
Q

PNS divisions

A
  • sensory (afferent): somatic + visceral

- motor (efferent): somatic + ANS (visceral)

22
Q

lumbar plexus nerves fct in general

A

-motor (somatic and ANS) and sensory (somatic and visceral)

23
Q

lumbar plexus nerves, parts of interest

A
  • lumbosacral trunk (L4 and L5) = uppermost part of the sciatic nerve
  • obturator n (L2,3,4) (through obturator canal to medial thigh muscles and skin)
24
Q

sacral plexus: where levels S1,2,3,4 come from anatomically

A

come out of the anterior sacral foramina

25
Q

ventral rami of sacral plexus are where in the pelvis

A

on top of piriformis

dorsal rami go to the back

26
Q

sciatic n levels + is what two nerves later

A

L4 to S3. comes out above piriformis in greater sciatic foramen

  • common fibular n
  • tibial n
27
Q

pudendal n levels and fct

A

S2,3,4

  • motor (somatic and ANS)
  • sensory (somatic and visceral)
28
Q

how not to confuse lumbosacral trunk with the S1 level

A

lumbosacral trunk crosses the ala of the sacrum and NOT the sacral promontory

29
Q

where are the sacral nerves in the pelvis

A

above piriformis (makes sense bc said before that ventral rami are above piriformis)

30
Q

regions where the pudendal n is travelling

A
  1. pelvis (S2,3,4)
  2. gluteal region
  3. pudendal canal (start of canal = gives off hemorrhoidal (inferior rectal) n). middle of canal gives off perineal n.
  4. deep perineal space
  5. dorsum of the penis (where becomes dorsal n of the penis). travels with the deep dorsal arteries (from dorsal penile a) + the deep dorsal veins between Buck’s fascia and the tunica albugenia
31
Q

inferior rectal n and a path taken

A
  1. leave the pudendal a and n but stay in the pudendal canal
  2. leave the pudendal canal
  3. go towards the anal sphincter
32
Q

PSS innervation of the pelvis

A

pelvic splanchnic nerves

  • originate from ventral rami of S2,3,4
  • travel on each side of pelvis THROUGH inferior hypogastric plexus (a SS structure) (on lat rectal and bladder walls)
  • after reach lat rectal wall, go to distal third of transverse colon, sigmoid colon, rectum, bladder, genitalia. preganglionic fibers synpase in the walls of the organs
  • don’t synapse in hypogastric plexus*
33
Q

SS innervation to pelvis

A

sup and inf hypogastric plexi

  • white rami communicantes go from spinal cord to SS trunk ganglia from T1 to L2 (T5 and below don’t synapse there). the chain continues below L2 height until S3
  • these two plexi arise from the lowest levels of the SS chain
  • pregang fibers synapse in the inferior hypogastric plexus**, then go to organs via blood vessels pathway
34
Q

hypogastric nerves def

A

nerves between the ONE superior hypogastric plexus in the body and the TWO inferior hypogastric plexi (one on each side). so there are TWO hypogastric nerves

35
Q

what SS fibers synapse in the sacral part of the SS chain

A

postganglionic fibers that start at the SS chain (sacral) and that travel through rami levels S2,3,4 to leave the pelvis via the sacral foramina and reach the sciatic nerve

36
Q

sacral splanchnic nerves def

A

sympathetic nerves extending from the SS chain ganglia to the inferior hypogastric plexus

37
Q

where to recognize pelvic splanchnic nerves if can find them

A

back wall of pelvis, on sacrum, exited sacral foramina with the sacral nerves

38
Q

SS inn to the leg is done how

A

postgang fibers leaving hypogastric plexus reach a sacral nerve (S1) (or postgang fibers leaving SS chain and going to sciatic n) and go to the leg

39
Q

SS inn of the pelvis comes from which nerves and plexus

A
  • SS chain to sacral splanchnic nerves going to hypogastric plexus
  • SS chain to sup hypogastric plexus to hypogastric nerves to inferior hypogastric plexus
40
Q

superior hypogastric plexus is located where

A

over the aorta at level of bifurcation

41
Q

sacral sympathetic chain relates to what nearby structure in the pelvis

A

is below the lateral sacral a

42
Q

how to recognize pelvic splanchnic n vs sacral splanchnic n

A
  • sacral splanchnic n leave the SS chain ganglia

- pelvic splanchnic n come off the sacral n and go out

Bloc I - Reproduction (57 decks)

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